A New Mexico teen will soon learn if he will be charged as an adult or juvenile after pleading guilty to the 2013 shooting deaths of his parents and three young siblings.

Yahoo News reports Nehemiah Griego is slated to learn his fate at a mid-January hearing after entering his plea late last week in state children's court. The now 18-year-old teen has been held in custody since he was 15, over which time he has received extensive medical and psychological treatment from the state.

"The parties believe that this agreement is the best resolution for Mr. Griego and the State, as well as for the victim's family, which was fully apprised of the agreement in advance of (the) plea hearing," Griego's attorney Jeffrey Buckels said in a statement.

Depending on if he is sentenced as a juvenile or an adult, Griego faces a potential sentence of anything ranging from probation to three life sentences plus 30 years. If state officials elect to sentence him as a juvenile, he could be released from the custody of the Children, Youth and Families department as early as by the time he is 21.

After opening fire on his family, authorities have claimed Griego reloaded his parents' two semiautomatic rifles and planned to take off for a nearby Wal-Mart where he planned to prey on unsuspecting shoppers. As it was, Griego ironically spent most of the rest of that day wandering the grounds of his church where congregation members were being trained on how to deal with a shooter.

Griego's parents, Greg and Sarah, were known throughout the community for their ministry work with work with inmates at a nearby jail, with Army vet Greg also serving as a pastor to one of Albuquerque's largest churches and as a volunteer chaplain to the local fire department.

Authorities have also revealed the teen later admitted he was angry with his mom before the shooting and long before had been experiencing both homicidal and suicidal thoughts.

Buckels told the court he and other lawyers for Griego have been in constant contact with their client's extended family members and they thought it best that the case not proceed to trial.